Because of the long history of the use of formalin as the standard fixative for tissue processing in histopathology, there are a large number of archival formalin-fixed and paraffin-embedded (FFPE) tissue banks worldwide. These FFPE tissue collections, with the attached clinical and outcome information, present invaluable resources for conducting retrospective protein biomarker investigations. However, the high degree of covalently cross-linked proteins in FFPE tissues hinders efficient extraction of proteins from tissue sections and prevents subsequent bioanalytical efforts from opening the door to a veritable treasure trove of information sequestered in archival tissue banks. Thus, this project aims to address methodological optimization for achieving effective protein extraction from FFPE tissues together with technological development for performing comprehensive and comparative studies of protein expression profiles within FFPE tissue specimens. By combining Calibrant's ability to enable proteomic profiling from minute protein samples with the technology and expertise offered by Professor Clive R. Taylor (University of Southern California School of Medicine) in antigen retrieval (AR)-immunohistochemistry (IHC) and tumor pathology, the proposed research represents a synergistic effort toward the evaluation and validation of a novel biomarker discovery paradigm on the basis of years of archived FFPE tissue collections. The specific aims for R41 Phase and the respective scientific milestones are: Specific Aim 1. Evaluation and optimization of protein recovery from FFPE tissues using AR approaches coupled with Gemini proteome platform (Months 1-12). Scientific Milestone: Selection of an optimal protein recovery protocol to be employed in proteome investigations using a "test battery" AR approach and IHC staining for a panel of 10-20 proteins. Specific Aim 2. Validation and quantification of antigens retrieved from FFPE tissue specimens (Months 13-24). Scientific Milestone: Demonstration of a sample consumption of 5 microgram total protein or less for an average of 5 peptides in each protein identification and the identification of at least 3,000 high confidence proteins with greater than 80% reproducibility in identified proteins among triplicates of identical FFPE tissue using combined AR and Gemini technologies. Direct comparison of IHC results and proteomic display will be attempted for a panel of 10-20 proteins. [unreadable] [unreadable] [unreadable]